<!DOCTYPE html>
<html>
<head>
	<meta charset="utf-8">
	<meta name="viewport" content="width=device-width, initial-scale=1">
	<title>CSS Margin 负值问题</title>
</head>
<style type="text/css">
	*{
		margin: 0;
		padding: 0;
	}
	.box{
		width: 200px;
		height: 200px;
		margin: 0 auto;
		border: 2px solid red;
		padding: 5px;
	}
	.box div{
		width: 100px;
		height: 100px;
		background-color: red;
		float: left;
	}
	.box div:nth-child(1){
		margin-right: -20px;
	}
	.box div:nth-child(2){
		background-color: blue;
		opacity: 0.8;
	}
</style>
<body>
	<div class="box">
		<div></div>
		<div></div>
	</div>
</body>
</html>
